1. Field of the Invention
This invention relates to a sheet treating apparatus for use in a recording apparatus or the like for recording images on sheet film.
2. Related Background Art
In a laser imager for recording on film an image signal obtained by the use of a diagnosing apparatus such as CT or MRI, the image signal inputted is first modulated into the intensity of a laser beam, and then this laser beam is applied to the film and the film is sensitized in conformity with the density of the image to thereby effect recording. Subsequently, the sensitized film is developed by a developing apparatus, whereby an image having light and shade conforming to the image signal is obtained on the film. High harmony is required of film for medical treatment images according to the prior art and therefore, film having silver salt emulsion applied thereto is sensitized with intensity conforming to an image to thereby effect recording, and the film is subjected to the so-called wet type developing process in which the film is immersed in developing liquid and fixating liquid for a predetermined time to thereby effect a developing process.
Such a wet type developing process, however, uses chemical liquids such as developing liquid and fixating liquid and is therefore cumbersome in treatment. Also, these chemical liquids become deteriorated and unusable when a predetermined process is carried out and therefore, it is necessary to interchange them suitably. The chemical liquids after used need be disused, and there is the inconvenience that the waste liquids produced at such time cause environmental problems.
So, there has been proposed a so-called dry type silver salt system which is similar to the wet type developing process in using film having silver salt emulsion applied thereto, but applies a laser beam to the film to effect recording, and thereafter carries out a heating process to thereby develop the film. An example of such dry type silver salt system is disclosed in Japanese Patent Application Laid-Open No. 53-34515. Also, various kinds of heat developing apparatuses for use in such dry type silver salt system have heretofore been proposed, and an example of them is one disclosed in Japanese Patent Publication No. 55-28927 or U.S. Pat. No. 5,411,825. It is possible to couple such a heat developing apparatus to a laser imager as described in U.S. Pat. No. 5,210,616 and effect recording and development by the use of film of the above-described dry type silver salt type instead of wet type film.
FIG. 10 of the accompanying drawings shows the construction of a laser image using such a dry type silver salt system. A supply magazine 2 and a receive magazine 3 are provided in parallel in a recording apparatus 1, and an optical unit 4 for applying a laser beam L downwardly is provided above the receive magazine 3. A heat developing apparatus 6 having a developing roller 5 is provided on the left side of the recording apparatus 1, and this heat developing apparatus 6 is formed with an opening 6a for discharging film F therethrough. The solid line in FIG. 10 indicates the conveyance path of the film F.
The unrecorded film F in the supply magazine 2 passes along the conveyance path and recording by the laser beam L is effected on the film F below the optical unit 4. Further, this film F is conveyed to the heat developing apparatus 6, is developed by the developing roller 5 and is discharged from the opening 6a in the heat developing apparatus 6.
However, when such a heat developing apparatus 6 is used in the laser imager, it is necessary to heat the recorded film F for a predetermined time, e.g. 10 seconds, and therefore, when the recorded film F is to be heated and developed while it is conveyed, if the throughput of recording, i.e., the number of sheets of film capable of being treated within a unit time, is taken into account, the speed of conveying the film cannot be made very low and the film must be heated over a very long distance. Therefore, the diameter of the rotatable developing roller 5 is made considerably large and thus, the dimensions of the entire apparatus becomes large.
Further, the film F is heated and developed while being twined around the developing roller 5, and this also leads to the problem that the film F becomes curled.
There is also the problem that particularly the characteristic of the laser which is a recording light source is varied by the heat generated from the heat developing apparatus 6 or the temperature of the film F during recording rises and when recording is to be continuously effected, the recording characteristic changes between the film F recorded at first and the film F recorded later.